This patent application claims priority on Finnish Patent Application No. 952926, filed Jun. 14, 1995.
The present invention relates to methods and means of suppressing food-induced hypersensitivity reactions in patients suffering from food allergy. Particularly the invention provides methods of preventing or treating allergies, especially cow""s milk allergy in infants. The invention also relates to development of specific formulae for allergic infants with impaired gut barrier function.
Cow""s milk allergy (CMA) is defined as an immune-mediated adverse reaction to cow""s milk proteins. The present treatment of choice is the complete elimination of cow""s milk antigens. In infants with CMA, it is necessary to use a substitute formula when human milk is unavailable. Hydrolysed formulae, based on cow""s milk-derived whey or casein, are used to provide adequate nutrition with a reduced antigenic load. The preliminary heat treatment of cow""s milk mainly affects the conformation of proteins and facilitates their hydrolysis. Subsequent enzymatic hydrolysis with pepsin, trypsin, pancreatic extracts and extracts from the intestinal mucosa causes progressive destruction of sequential epitopes and refines the formulae into the least antigenic and allergenic form.
In most cases, extensively hydrolysed cow""s milk-derived formulae can be safely introduced and these are efficient and clinically and metabolically well tolerated. Enzymatic hydrolysis, however, does not necessarily make the formula nonallergenic, as the optimal extent of hydrolysis is not known and traces of the original protein are detected in the hydrolysate. Therefore, introduction of these substitutes to children with cow""s milk allergy must be cautious.
The approach to control allergic inflammation by antigen elimination has not been satisfactory, particularly in patients with multiple food allergies (Sampson et al., 1992). These patients frequently show increased intestinal permeability and dysfunction of the intestine""s defence barrier (Majamaa et al., 1996, Majamaa and Isolauri, 1996). This enhances the risk for growth disorders and sensitization to multiple foods. New approaches are urgently needed for the treatment of cow""s milk allergy to improve the substitute formulae in CMA.
Intestinal antigen handling determines subsequent immune response to the antigen. In health, antigens are absorbed across epithelium along two functional pathways. The main pathway is degradative reducing the immunogenicity of the antigen. A minor pathway allows the transport of intact proteins which is crucial for antigen-specific immune responses. Aberrant antigen absorption enhances the sensitization process (Fargeas et al., 1995).
Differential production of cytokines by T-helper (Th) cells during an immune reaction has important regulatory effects on the nature of th e immune response. The cytokine pro file of the natural immune response determines the phenotype of the subsequent specific immune response. Apart from controlling IgE synthesis, IL-4 is crucial for the development and maturation of the Th2 phenotype, characterized for allergic inflammation.
This process appears crucial for the development of tolerance to ingested protein. Oral tolerance is a state of antigen-specific systemic non-responsiveness characterized by local antigen-specific IgA response.
An isolated human intestinal strain, Lactobacillus strain GG (Lactobacillus GG, ATCC 53103) has recently been shown to promote local IgA responses against dietary antigens encountered by the enteric route and may therefore aid in immune elimination (Isolauri et al., 1993). It is not as yet known whether particular strains of intestinal bacteria could directly modify the immunogenicity of the food antigens and consequently downregulate hypersensitivity reactions.
Lactobacilli are included in the microbial flora of healthy intestines. It has been assumed that Lactobacilli act in the intestinal tract by competing for receptors and nutrients against pathogenic microbes on the intestinal mucosa.
Probiotics are viable microbial preparations which promote health by maintaining the natural microflora in the gut. A microbial preparation can be acknowledged as a probiotic if the functioning microbes thereof and their mode of action are known. The probiotics attach on the intestinal mucosa, colonize the human intestinal tract and prevent attachment of harmful microbes. A crucial presumption is that they get up to the gut""s mucosa and do not get destroyed in the upper part of the gastrointestinal tract. Lactobacillus GG is one of known bacteria having probiotic characteristics.
The present inventors have now found that certain bacteria of the gastrointestinal tract, especially Lactobacilli, and especially bacteria having probiotic characteristics, can be used to enhance the efficacy of elimination diets and to improve the oral tolerance, in preventing or treating food-induced hypersensitivity reactions in a patient.
One aspect of the invention is that protein hydrolysates obtained by hydrolysis of proteins with above mentioned gastrointestinal bacteria can also be used to said purpose. We show here that protein hydrolysates obtained according to this invention have an immunological effect promoting hypoallergenicity. The hydrolysates downregulate hypersensitivity reactions thus promoting the gut immune barrier function, i.e. stabilising the gut mucosal barrier.
The present invention provides an improved protein hydrolysate formula downregulating hypersensitivity reactions and promoting the gut immune barrier function. The hydrolysate formula is obtainable by hydrolysing proteins with enzymes obtained from probiotic gastrointestinal bacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103), and with trypsin and/or pepsin.
Alternatively, a protein hydrolysate formula of the invention can be obtained by hydrolysing proteins with trypsin and/or pepsin, and adding to the hydrolysate so obtained a bacterial preparation comprising probiotic gastrointestinal bacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103). The bacteria are added into the hydrolysate formula preferably as a lyophilized preparation.
While administering such a hydrolysate formula to a patient, it is to be expected that the hydrolysing enzymes of the bacteria present are released in vivo whereby the same effect is achieved as with an improved hydrolysate formula as defined above. In addition, the viable bacteria stabilize the gut mucosal barrier enhancing the local defence.
An embodiment of this invention is a method of preventing or treating food-induced hypersensitivity reactions in an infant, which method comprises the step of administering to an infant at risk the improved protein hydrolysate formula of the invention, or alternatively a protein hydrolysate formula together with a bacterial preparation comprising probiotic gastrointestinal bacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103).
A further embodiment of this invention is a method of treating cow""s milk allergy in a patient, comprising administering to the patient the improved protein hydrolysate formula of the invention or, alternatively administering a protein hydrolysate formula together with a bacterial preparation comprising probiotic gastrointestinal bacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103).
The invention also provides a method of promoting tolerogenic immune responses to food antigens in a patient, comprising oral administration of the improved protein hydrolysate formula of the invention to the patient, or, alternatively, a bacterial preparation comprising probiotic gastrointestinal bacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103), or, alternatively, a protein hydrolysate formula together with a bacterial preparation comprising probiotic gastrointestinal bacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103).
In the methods of the invention as defined above, when a protein hydrolysate formula is used in combination with selected probiotic bacteria as defined above, such a formula can be any suitable protein hydrolysate formula, known or novel. It can thus be either a partial protein hydrolysate, or alternatively an extensively hydrolysed formula. Preparation of a protein hydrolysate suitable for this purpose is disclosed e.g. in EP patent application No. 601 802.
Preferred bacterium to be used in the formulae and methods of the invention is Lactobacillus GG (ATCC 53103).
In this specification and in the appended claims the phrase xe2x80x9cbacteria, especially Lactobacilli, which have adhesive and colonizing characteristics and a protease enzyme system which are similar to those of the strain Lactobacillus GG (ATCC 53103)xe2x80x9d should be understood to define bacteria whose adhesive and colonizing characteristics are comparable to those of the LGG strain, e.g. as defined in EP-patent 199 535. These bacteria are also supposed to have same kind of enzyme system as LGG, which means that enzymes derived from such bacteria are able to degrade proteins to produce hydrolysation products with same effects as those obtained using enzymes derived from LGG.